databases/pgpool: Upgrade from 3.4.11 to 3.4.16
Changelogs:
- http://www.pgpool.net/docs/latest/en/html/release-3-4-12.html
- http://www.pgpool.net/docs/latest/en/html/release-3-4-13.html
- http://www.pgpool.net/docs/latest/en/html/release-3-4-14.html
- http://www.pgpool.net/docs/latest/en/html/release-3-4-15.html
- http://www.pgpool.net/docs/latest/en/html/release-3-4-16.html